Need quick suggestions for installation error

Hi,everyone!
I have a serious problem while creating my wordpress blog. Actually I am starting it on localhost(wamp server). I had finished up everything like giving database name,user name ,password and clicked on submit button then again i finished up the next step. then i tried logging in to http://localhost/wordpress/wp-admin/ but it is giving an error…
Notice: Use of undefined constant ABSPATH – assumed ‘ABSPATH’ in C:\wamp\www\wordpress\wp-admin\admin.php on line 10

Warning: require_once(ABSPATHwp-admin/includes/bookmark.php) [function.require-once]: failed to open stream: No such file or directory in C:\wamp\www\wordpress\wp-admin\admin.php on line 10

Fatal error: require_once() [function.require]: Failed opening required ‘ABSPATHwp-admin/includes/bookmark.php’ (include_path=’.;C:\php5\pear’) in C:\wamp\www\wordpress\wp-admin\admin.php on line 10.
Although I must mention that I have made changes in wp-config.php page changing the DB_name,username…etc. but still i am getting this error please help me solve this problem.
All solutions will be greatly appreciated.
Thanks
lokesh